Combustion engines operating according to the four stroke principle customarily have gas exchange valves in the form of inlet and outlet valves in order to be able to carry out the gas exchange required for operating the internal combustion engine. Opening and closing movements of the particular valves are initiated here via cams of an associated valve camshaft.
In the sphere of spark ignition engines, use is furthermore customarily made of adjustment devices via which the timings of the gas exchange valves can be displaced by means of rotation of the valve camshaft and can therefore be adapted to different rotational speeds and cylinder fillings of the internal combustion engine. This makes it possible to increase the quality of the gas exchange.
DE 102 48 351 A1 discloses a valve drive for controlling gas exchange valves of an internal combustion engine, in which a valve camshaft which is mounted within a cylinder head of the internal combustion engine can be set into rotation via a driving disk. In this case, an adjustment device is provided on the end side of the valve camshaft, which adjustment device has an adjustment motor, which is located in an additional housing outside the cylinder head, and a gearing, wherein the adjustment motor is connected to the valve camshaft via the gearing located in between. When the adjustment motor is actuated, relative rotation of the valve camshaft with respect to the driving disk can be achieved by means of the gearing, which leads to a displacement of the actuation of the gas exchange valves taking place via cams of the valve camshaft.
However, an arrangement of this type has the disadvantage that the internal combustion engine requires a greater amount of space because of the adjustment motor provided in the additional housing on the cylinder head.
It is therefore the object of the present invention to make available a valve drive for controlling gas exchange valves of an internal combustion engine, which valve drive has an adjustment device arranged as compactly as possible to provide a reduced overall length of the internal combustion engine.